Many products are manufactured from elongated sheet or stock material that is shipped and stored in the form of a roll or coil. Continuous strips or webs of thin, flexible material are commonly provided on storage rolls that are subsequently unwound for production of items made from these materials. Examples of these materials are plastic film, metal foil, tissue and paper.
During the manufacture of paper products such as napkins, newspapers, and magazines, for example, very large storage rolls of paper are used to provide the stock material from which the paper items are produced. The storage rolls are unwound for further processing such as cutting, folding or printing. The rolls of raw material may have a length of up to about 300 inches (750 cm) and a weight of up to about 8,000 lbs (3600 kg). Machines such as printing machines or laminating machines to which the sheet is supplied by the unwinding machine usually require the sheet to be supplied at a constant speed and tension. When nearly the entire roll has been unwound from the core, it is necessary for the machine to stop unwinding sheet from the almost empty roll and to commence unwinding sheet from a new roll without any interruption in the supply of sheets to the operating machine. It is thus necessary for the sheet to be cut from the nearly empty roll, and to be secured to the sheet on the new roll to ensure continuous supply of sheet.
Conventionally, the rolls of stock material are prepared for the winding and unwinding machine in a rather labor intensive operation that can sometimes present dangerous working conditions for the operator. The large rolls of material are usually delivered to a work station by conveyor or cart or the like. At the work station, the operator inserts plugs into each end of the roll of stock material. The operator then commonly uses an overhead crane to engage the plugs and lift the roll, of stock material off the conveyor or cart. The operator then prepares the roll for delivery to the unwinding machine. Such preparation usually involves cleaning the surface of the roll and positioning the leading edge of the web of stock material in a certain orientation. Using the overhead crane, the operator then lifts the prepared roll of material and delivers it to the unwinding station. The operator then uses the overhead crane to pick up a spent roll of material and return the spent roll to the work station wherein the operator removes whatever stock material remains on the core, removes the plugs, and delivers the spent core to a spent core storage area. It can be seen that having the operator in such close proximity with the large roll of stock material that sometimes can reach upwards of 8000 pounds presents many challenges for work place safety and efficiency.
Clearly, a need exists for a unique method to quickly change to a new roll once the previous roll is spent.